The mission of this Quantitative Analysis and Proteomics Core (QAPC) will be to provide comprehensive proteomic approaches for the individual projects of this NIEHS Center to detect and characterize PD-related proteins, especially with regard to S-nitrosylation (reaction of the NO group with critical cysteine thiol to regulate protein function) and further oxidation reactions. Core B will support the efforts of Project 1, Project 2, and Project 3 by analysis and quantification of PDrelated proteins and their possible S-nitrosylation (including SNO-parkin, SNO-DJ-1, and SNOprotein disulfide isomerase [SNO-PDI]) using multiple chemical and proteomic approaches. Core B will also support the efforts of Project 4 by detecting possible biomarkers represented by these SNO-proteins in a-synuclein-over-expressing or mitochondrial complex I inhibitor-treated in hESCderived neuronal cell models. This Core will also interact with Core E (High-throughput Chemical Library Screening) by providing DAN assays that detect S-nitrosylated proteins in 384- and 1536- well multiwell formats in order to screen for small molecules that prevent S-nitrosylation of PDrelated proteins such as parkin, DJ-1 and PDI. These small molecules will then be tested for neuroprotection in PD model systems in Projects 2, 3, and 4.